Protective sheath for flexible shafts



.4 5 5 A.. 8 6, l L H A T S N E F E R a sept. 1s, 1928.

PROTECTIVE SHEATH FOR FLEXIBLE SHAFTS Filed June 22, 1927 j. mi? wm.

J5? afa/721,921

GUS TAV RIEF'E'NST H L Patented Sept. 18, 1928. l

UNITED STATES PATENT ol-Fica GUSTV RIEFENSTAL, OF-BERLIN-TREPTOW, GERMANY, .ASSIGNOR TO DEUTSCHE .GOLD- UND SILBERSCHEIDEANSTALT, O F FRANKFORT-CN-THE-MAIN, GLEBIANY.

PROTECTIVE SHEATH l'FOR FLEXIBLE SHAFTS Applica-tion led June 22, 1927, Serial No.1200,723, an'd in Germany June 23, 1986.

The invention relates to a protective sheath for fiexible shafts, and consists of two or more helical wire, coils which are of the same pitch but different diameters and are screwed one into the other to produce a closed sheath. The sheath can be employed for all kinds of flexible shafts for driving ma chinery of every description; it is particularly suitable for duplex joints 1n driving shafts :for dental drills.

According to the invention connecting sockets, which may be of various forms, are

' provided at the ends of the sheath. The

sockets may be provided with annular cavi-'- ties to'enable them to be attached to the helical sheath, the' ends of the sheath fitting into the cavities and being advantageously soldered in. Another method of attaching the sockets to the sheath is by providing each of them with an extended neck over which the reason of changing strains.

corresponding end of the sheath is` drawn. The'socket may, however, be screw threaded to suit ,the cross section and pitch of the inner or outer coil, the corresponding end of the coil being screwed on or in the screw thread.

It is particularly advantageous to provlde the screw thread externally upon the extended neck upon which the sheath is screwed.

In order to facilitate loosenin of the sheath on the sockets, when desire each 1s provided with a rotary part havlng projections which abut against the iiat aces of the ends of the wires of the coils, so that when lrotated it opens the coils.

It is known to encloseiexible shafts and duplex joints in protective sheaths consisting of flexible metal tubes or simple metal helices provided `wit-h a leather covering. The metal tubes, however, are only provided with a limited amount of iiexibility and do not allow sufficiently for the variations in length to which more particularly the dii-- plex joints are continuously subjected by- The more Hexible simple leather covered helices also have this disadvantage and furthermore if the shafts break the leather covering and particularly the duplex joints Aare nearly always effected by the sharp upwardly bending ends of the duplex springs. The protective sheath according to the invention avoids all these disadvantages and allows bends in the duplex joints that form complete loops.

Two forms of the protective sheath accordends ,of the sheath.

ing to the invention vare illustrated by way of example in the accompanying drawings, 1n whlch:

Figure 1 is an illustration ofthe sheath with connecting sockets, partly in section and Figure 2 1s a part sectional view showing a modified form ofconnectionbetween sheath and socket with means for facilitating removal. h

Flgure 3 being a plan of said means shown sired form. Furthermore, wires may be used they form a closed sleeve. l v

The sheath is provided at its ends withv having two diiierent cross sections, so long as sockets 3 and 4, the flanges 7 of which have.,

cavities 5 for the reception ofthe ends of the sheath and if necessary for solderingmate'- rial. The inner `wall of each cavity-5 is advantageousljT provided with an extended neck 6 over which are drawn the corresponding As shown in Figure 2, the ends of the sheath are screwed onto the extended necks 6 ofthe sockets 3 and4, the necks 6 being screw \y i threaded to correspond tothe cross section and the pitch of the inner coil 1. By suitably screw threading the outer wall of the cavity 5 the outer coil 2 insteadof the inner co1] could be screwed into the sockets. l l

It 1s not possible to loosen the sheath from the neck 6 by merely unscrewing the coils 1 and 2, as they would draw in together. A

special member is, however, provided to enable them to be unscrewed (Figures 2and 3). Thls conslsts of a rotary Vpart 8, which4 lis placed on the end of the sheath and which has a stop flange 9 engagingunder the endsof theb 10" l coils. 'On the' flange are mounted two teeth or projectlons 10, each of which engages with the flat face of the end 11 of a coil. When the part 10 is rotated the .coils 1 and 2 are slightly opened, thus rendering it possible for the l0 sheath to be unscrewed from the neck 6. The

same purpose could be served by one stop or projection 10 that opens a coil upon the rota# t'ion of the part 8; two stops, however,I are n preferable for certainty of action.

I claim: 1. A protective sheath for flexible vshafts comprising at least two helical Wire coils' of equal pitch and of different diameter screwed 5 together to form a closed sheath, connecting sockets at the ends of said coils, rotary members on said sockets, flanges underlying the ends of the coils on said rotary members, and projections on said flanges for engaging the 10 ends of the wires of the coils.

` 2. In combination, a. flexible tubing comprising at least two helical wire coils screwed together to form a closed tube, sockets connected to atleast one of said coils at the ends thereof, and means upon said sockets for holding said ends stationary `while rotatingl said sockets relative thereto.

In testimony whereof I affix my signature.

GUSTAV RIEFENSTAHL. 

